The invention relates to pressurized water nuclear reactor fuel assemblies of the type having upper and lower end fittings joined by guide tubes or thimbles upon which are mounted spaced fuel rod support grids for holding hollow clad fuel rods of nuclear fuel with solid end caps thereon.
There is a need, when assembling or reassembling fuel rods in the individual cells of the fuel assembly grids, to provide guidance as the fuel rod is inserted into and through a fuel assembly grid. Properly guided fuel rods during fuel rod loading prevent possible grid damage and fuel rod hangup.
Most producers of nuclear fuel have provided their fuel rods with end configurations which facilitate the use of gripper tools for loading and reconstitution. These configurations were designed to prevent grid damage during fuel rod insertion when used with specific grid designs. Some utilities, especially those in Europe, perform their own fuel assembly repair and reconstitution. In many cases, these utilities have purchased special tooling to perform these operations. Therefore, they do not want the fuel rod end configurations changed. In fact, some utilities have made it a requirement to maintain the same fuel end configuration for reload batches.